The present invention concerns a procedure and a device for influencing the density distribution of wood chips to be spread over a specific width.
The problem of uniform spreading of wood chips has long been known. For example, German Pat. No. 2214 900 suggests a spreader device for equalization of different surface weights in the transverse direction of wood or fiber chips or similar materials, for the production of particle boards, fiber boards, and the like. A form base below the spreader device and movable in relation thereto is provided with a flexible conveyor belt for dosage, arranged above the form base and sliding along a support, and with a stripper roll rotating over the same, vertically to the transport direction, for the chips, fibers, or the like which have been spread over the dosage conveyor belt. The width of the opening between the dosage conveyor belt and the stripper roll varies over its length. The height of the dosage conveyor belt below the stripper roll is continuously adjusted in the transverse direction. The purpose of this device is to influence the quantity of chips exiting between the stripper roll and the dosage conveyor belt, which quantity is subsequently being spread, all this in respect to the distribution of surface weight.
As a consequence of the increased discharge performance of such dosage containers, the discharge process is currently executed according to the method disclosed in German Pat. No. 1084 199. By means of the spiked rollers arranged one above the other, the chip goods are milled off over the entire cross section of the supply of chips.
However, it has been found that in this case, it is not possible to utilize a device according to German Pat. No. 2214 900 for equalization of varying surface weights of wood or fiber chips or the like in the transverse direction, when particle boards, fiber boards, etc., are being produced, since the elevation of the base belt causes merely a local concentration of the chip goods, without effecting a change in the discharge.
Currently, even when spreader machines are utilized where the discharge and the spreading of chip goods no longer are executed through an opening between the supply container and the stripper roll and the subsequent strike-off roll but rather by means of a cascade from discharge rollers arranged above one another and developed as spiked rolls, system-related errors still occur in the chips that have been spread. These errors, in turn, cause errors in the density. Also, it is impossible to press the spread-out chips with a predetermined density distribution.